1 /*
2 * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/javaClasses.inline.hpp"
27 #include "gc/parallel/mutableSpace.hpp"
28 #include "gc/parallel/parallelScavengeHeap.hpp"
29 #include "gc/parallel/psOldGen.hpp"
30 #include "gc/parallel/psPromotionManager.inline.hpp"
31 #include "gc/parallel/psScavenge.inline.hpp"
32 #include "gc/shared/gcTrace.hpp"
33 #include "gc/shared/preservedMarks.inline.hpp"
34 #include "gc/shared/taskqueue.inline.hpp"
35 #include "logging/log.hpp"
36 #include "logging/logStream.hpp"
37 #include "memory/allocation.inline.hpp"
38 #include "memory/iterator.inline.hpp"
39 #include "memory/memRegion.hpp"
40 #include "memory/padded.inline.hpp"
41 #include "memory/resourceArea.hpp"
42 #include "oops/access.inline.hpp"
43 #include "oops/compressedOops.inline.hpp"
44
45 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
46 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = NULL;
47 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = NULL;
48 PSOldGen* PSPromotionManager::_old_gen = NULL;
49 MutableSpace* PSPromotionManager::_young_space = NULL;
50
51 void PSPromotionManager::initialize() {
52 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
53
54 _old_gen = heap->old_gen();
55 _young_space = heap->young_gen()->to_space();
56
57 const uint promotion_manager_num = ParallelGCThreads + 1;
58
59 // To prevent false sharing, we pad the PSPromotionManagers
60 // and make sure that the first instance starts at a cache line.
61 assert(_manager_array == NULL, "Attempt to initialize twice");
62 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
63
64 _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
65
66 // Create and register the PSPromotionManager(s) for the worker threads.
67 for(uint i=0; i<ParallelGCThreads; i++) {
68 stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
69 }
70 // The VMThread gets its own PSPromotionManager, which is not available
71 // for work stealing.
72
73 assert(_preserved_marks_set == NULL, "Attempt to initialize twice");
74 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
75 _preserved_marks_set->init(promotion_manager_num);
76 for (uint i = 0; i < promotion_manager_num; i += 1) {
77 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
78 }
79 }
80
81 // Helper functions to get around the circular dependency between
82 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
83 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
84 return PSScavenge::should_scavenge(p, check_to_space);
85 }
86 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
87 return PSScavenge::should_scavenge(p, check_to_space);
88 }
89
90 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
91 assert(index < ParallelGCThreads, "index out of range");
92 assert(_manager_array != NULL, "Sanity");
93 return &_manager_array[index];
94 }
95
96 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
97 assert(_manager_array != NULL, "Sanity");
98 return &_manager_array[ParallelGCThreads];
99 }
100
101 void PSPromotionManager::pre_scavenge() {
102 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
103
104 _preserved_marks_set->assert_empty();
105 _young_space = heap->young_gen()->to_space();
106
107 for(uint i=0; i<ParallelGCThreads+1; i++) {
108 manager_array(i)->reset();
109 }
110 }
111
112 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
113 bool promotion_failure_occurred = false;
114
115 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
116 for (uint i = 0; i < ParallelGCThreads + 1; i++) {
117 PSPromotionManager* manager = manager_array(i);
118 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
119 if (manager->_promotion_failed_info.has_failed()) {
120 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
121 promotion_failure_occurred = true;
122 }
123 manager->flush_labs();
124 }
125 if (!promotion_failure_occurred) {
126 // If there was no promotion failure, the preserved mark stacks
127 // should be empty.
128 _preserved_marks_set->assert_empty();
129 }
130 return promotion_failure_occurred;
131 }
132
133 #if TASKQUEUE_STATS
134 void
135 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
136 #define FMT " " SIZE_FORMAT_W(10)
137 out->print_cr("%3u" FMT FMT FMT FMT,
138 i, _array_chunk_pushes, _array_chunk_steals,
139 _arrays_chunked, _array_chunks_processed);
140 #undef FMT
141 }
142
143 static const char* const pm_stats_hdr[] = {
144 " ----partial array---- arrays array",
145 "thr push steal chunked chunks",
146 "--- ---------- ---------- ---------- ----------"
147 };
148
149 void
150 PSPromotionManager::print_taskqueue_stats() {
151 if (!log_is_enabled(Trace, gc, task, stats)) {
152 return;
153 }
154 Log(gc, task, stats) log;
155 ResourceMark rm;
156 LogStream ls(log.trace());
157 outputStream* out = &ls;
158 out->print_cr("== GC Tasks Stats, GC %3d",
159 ParallelScavengeHeap::heap()->total_collections());
160
161 TaskQueueStats totals;
162 out->print("thr "); TaskQueueStats::print_header(1, out); out->cr();
163 out->print("--- "); TaskQueueStats::print_header(2, out); out->cr();
164 for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
165 TaskQueueStats& next = manager_array(i)->_claimed_stack_depth.stats;
166 out->print("%3d ", i); next.print(out); out->cr();
167 totals += next;
168 }
169 out->print("tot "); totals.print(out); out->cr();
170
171 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
172 for (uint i = 0; i < hlines; ++i) out->print_cr("%s", pm_stats_hdr[i]);
173 for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
174 manager_array(i)->print_local_stats(out, i);
175 }
176 }
177
178 void
179 PSPromotionManager::reset_stats() {
180 claimed_stack_depth()->stats.reset();
181 _array_chunk_pushes = _array_chunk_steals = 0;
182 _arrays_chunked = _array_chunks_processed = 0;
183 }
184 #endif // TASKQUEUE_STATS
185
186 PSPromotionManager::PSPromotionManager() {
187 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
188
189 // We set the old lab's start array.
190 _old_lab.set_start_array(old_gen()->start_array());
191
192 uint queue_size;
193 claimed_stack_depth()->initialize();
194 queue_size = claimed_stack_depth()->max_elems();
195
196 _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
197 if (_totally_drain) {
198 _target_stack_size = 0;
199 } else {
200 // don't let the target stack size to be more than 1/4 of the entries
201 _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
202 (uint) (queue_size / 4));
203 }
204
205 _array_chunk_size = ParGCArrayScanChunk;
206 // let's choose 1.5x the chunk size
207 _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
208
209 _preserved_marks = NULL;
210
211 reset();
212 }
213
214 void PSPromotionManager::reset() {
215 assert(stacks_empty(), "reset of non-empty stack");
216
217 // We need to get an assert in here to make sure the labs are always flushed.
218
219 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
220
221 // Do not prefill the LAB's, save heap wastage!
222 HeapWord* lab_base = young_space()->top();
223 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
224 _young_gen_is_full = false;
225
226 lab_base = old_gen()->object_space()->top();
227 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
228 _old_gen_is_full = false;
229
230 _promotion_failed_info.reset();
231
232 TASKQUEUE_STATS_ONLY(reset_stats());
233 }
234
235 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
236 assert(_preserved_marks == NULL, "do not set it twice");
237 _preserved_marks = preserved_marks;
238 }
239
240 void PSPromotionManager::restore_preserved_marks() {
241 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
242 }
243
244 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
245 totally_drain = totally_drain || _totally_drain;
246
247 #ifdef ASSERT
248 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
249 MutableSpace* to_space = heap->young_gen()->to_space();
250 MutableSpace* old_space = heap->old_gen()->object_space();
251 #endif /* ASSERT */
252
253 PSScannerTasksQueue* const tq = claimed_stack_depth();
254 do {
255 ScannerTask task;
256
257 // Drain overflow stack first, so other threads can steal from
258 // claimed stack while we work.
259 while (tq->pop_overflow(task)) {
260 process_popped_location_depth(task);
261 }
262
263 if (totally_drain) {
264 while (tq->pop_local(task)) {
265 process_popped_location_depth(task);
266 }
267 } else {
268 while (tq->size() > _target_stack_size && tq->pop_local(task)) {
269 process_popped_location_depth(task);
270 }
271 }
272 } while ((totally_drain && !tq->taskqueue_empty()) || !tq->overflow_empty());
273
274 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
275 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
276 assert(tq->overflow_empty(), "Sanity");
277 }
278
279 void PSPromotionManager::flush_labs() {
280 assert(stacks_empty(), "Attempt to flush lab with live stack");
281
282 // If either promotion lab fills up, we can flush the
283 // lab but not refill it, so check first.
284 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
285 if (!_young_lab.is_flushed())
286 _young_lab.flush();
287
288 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
289 if (!_old_lab.is_flushed())
290 _old_lab.flush();
291
292 // Let PSScavenge know if we overflowed
293 if (_young_gen_is_full) {
294 PSScavenge::set_survivor_overflow(true);
295 }
296 }
297
298 template <class T> void PSPromotionManager::process_array_chunk_work(
299 oop obj,
300 int start, int end) {
301 assert(start <= end, "invariant");
302 T* const base = (T*)objArrayOop(obj)->base();
303 T* p = base + start;
304 T* const chunk_end = base + end;
305 while (p < chunk_end) {
306 if (PSScavenge::should_scavenge(p)) {
307 claim_or_forward_depth(p);
308 }
309 ++p;
310 }
311 }
312
313 void PSPromotionManager::process_array_chunk(PartialArrayScanTask task) {
314 assert(PSChunkLargeArrays, "invariant");
315
316 oop old = task.to_source_array();
317 assert(old->is_objArray(), "invariant");
318 assert(old->is_forwarded(), "invariant");
319
320 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
321
322 oop const obj = old->forwardee();
323
324 int start;
325 int const end = arrayOop(old)->length();
326 if (end > (int) _min_array_size_for_chunking) {
327 // we'll chunk more
328 start = end - _array_chunk_size;
329 assert(start > 0, "invariant");
330 arrayOop(old)->set_length(start);
331 push_depth(ScannerTask(PartialArrayScanTask(old)));
332 TASKQUEUE_STATS_ONLY(++_array_chunk_pushes);
333 } else {
334 // this is the final chunk for this array
335 start = 0;
336 int const actual_length = arrayOop(obj)->length();
337 arrayOop(old)->set_length(actual_length);
338 }
339
340 if (UseCompressedOops) {
341 process_array_chunk_work<narrowOop>(obj, start, end);
342 } else {
343 process_array_chunk_work<oop>(obj, start, end);
344 }
345 }
346
347 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
348 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
349
350 // Attempt to CAS in the header.
351 // This tests if the header is still the same as when
352 // this started. If it is the same (i.e., no forwarding
353 // pointer has been installed), then this thread owns
354 // it.
355 if (obj->cas_forward_to(obj, obj_mark)) {
356 // We won any races, we "own" this object.
357 assert(obj == obj->forwardee(), "Sanity");
358
359 _promotion_failed_info.register_copy_failure(obj->size());
360
361 push_contents(obj);
362
363 // Save the markWord of promotion-failed objs in _preserved_marks for later
364 // restoration. This way we don't have to walk the young-gen to locate
365 // these promotion-failed objs.
366 _preserved_marks->push_always(obj, obj_mark);
367 } else {
368 // We lost, someone else "owns" this object
369 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
370
371 // No unallocation to worry about.
372 obj = obj->forwardee();
373 }
374
375 log_develop_trace(gc, scavenge)("{promotion-failure %s " PTR_FORMAT " (%d)}", obj->klass()->internal_name(), p2i(obj), obj->size());
376
377 return obj;
378 }